Outlining his position on immigration in August of last year, Donald Trump, then the Republican candidate for U.S. president, made his motivating philosophy clear: “There is only one core issue in the immigration debate, and that issue is the well-being of the American people.” Although this nationalistic appeal may strike some readers as conservative, it is very similar to the position taken by U.S. civil rights icon and Democrat Barbara Jordan, who before her death in 1996 headed President Bill Clinton’s commission on immigration reform. “It is both a right and a responsibility of a democratic society,” she argued, “to manage immigration so that it serves the national interest.” Trump’s rhetoric has of course been overheated and insensitive at times, but his view on immigration—that it should be designed to benefit the receiving country—is widely held.In the United States, there is strong evidence that the national interest has not been well served by the country’s immigration policy over the last five decades. Even as levels of immigration have approached historic highs, debate on the topic has been subdued, and policymakers and opinion leaders in both parties have tended to overstate the benefits and understate or ignore the costs of immigration. It would make a great deal of sense for the country to reform its immigration policies by more vigorously enforcing existing laws, and by moving away from the current system, which primarily admits immigrants based on family relationships, toward one based on the interests of Americans.IMMIGRANT NATIONTrump did not create the strong dissatisfaction with immigration felt by his working-class supporters, but he certainly harnessed it. Voters’ sense that he would restrict immigration may be the single most important factor that helped him win the longtime Democratic stronghold of the industrial Midwest, and thus the presidency. There are two primary reasons why immigration has become so controversial, and why Trump’s message resonated. The first is lax enforcement and the subsequently large population of immigrants living in the country illegally. But although illegal immigration grabs most of the headlines, a second factor makes many Americans uncomfortable with the current policy. It is the sheer number of immigrants, legal or otherwise. The United States currently grants one million immigrants lawful permanent residence (or a “green card”) each year, which means that they can stay as long as they wish and become citizens after five years, or three if they are married to a U.S. citizen. Roughly 700,000 long-term visitors, mostly guest workers and foreign students, come annually as well. Such a large annual influx adds up: In 2015, data from the U.S. Census Bureau indicated that 43.3 million immigrants lived in the country—double the number from 1990. The census data include roughly ten million illegal immigrants, while roughly a million more go uncounted. In contrast to most countries, the United States grants citizenship to everyone born on its soil, including the children of tourists or illegal immigrants, so the above figures do not include any U.S.-born children of immigrants.

Proponents of immigration to the United States often contend that the country is a “nation of immigrants,” and certainly immigration has played an important role in American history. Nevertheless, immigrants currently represent 13.5 percent of the total U.S. population, the highest percentage in over 100 years. The Census Bureau projects that by 2025, the immigrant share of the population will reach 15 percent, surpassing the United States’ all-time high of 14.8 percent, reached in 1890. Without a change in policy, that share will continue to increase throughout the twenty-first century. Counting immigrants plus their descendants, the Pew Research Center estimates that since 1965, when the United States liberalized its laws, immigration has added 72 million people to the country—a number larger than the current population of France.

Given these numbers, it is striking that public officials in the United States have focused almost exclusively on the country’s 11 to 12 million illegal immigrants, who account for only one quarter of the total immigrant population. Legal immigration has a much larger impact on the United States, yet the country’s leaders have seldom asked the big questions. What, for example, is the absorption capacity of the nation's schools and infrastructure? How will the least-skilled Americans fare in labor market competition with immigrants? Or, perhaps most importantly, how many immigrants can the United States assimilate into its culture? Trump has not always approached these questions carefully, or with much sensitivity, but to his credit he has at least raised them.

TIMES CHANGERegarding cultural assimilation, advocates of open immigration policies often argue that there is no problem. During the last great wave of immigration, from roughly 1880 to 1920, Americans feared the newcomers would not blend in, but for the most part they ended up assimilating. Therefore, as this reasoning goes, all immigrants will assimilate.Immigrants currently represent 13.5 percent of the total U.S. population, the highest percentage in over 100 years.Unfortunately, however, circumstances that helped Great Wave immigrants assimilate are not present today. First, World War I and then legislation in the early 1920s dramatically reduced new arrivals. By 1970 less than 5 percent of the U.S. population was foreign-born, down from 14.7 percent in 1910. This reduction helped immigrant communities assimilate, as they were no longer continually refreshed by new arrivals from the old country. But in recent decades, the dramatic growth of immigrant enclaves has likely slowed the pace of assimilation. Second, many of today’s immigrants, like those of the past, have modest education levels, but unlike in the past, the modern U.S. economy has fewer good jobs for unskilled workers. Partly for this reason, immigrants do not improve their economic situation over time as much as they did in the past. Third, technology allows immigrants to preserve ties with the homeland in ways that were not possible a century ago. Calling, texting, emailing, FaceTiming, and traveling home are all relatively cheap and easy.Fourth, the United States’ attitude toward newcomers has also changed. In the past, there was more of a consensus about the desirability of assimilation. Supreme Court Justice Louis Brandeis, the son of Jewish immigrants, said in a 1915 speech on “True Americanism” that immigrants needed to do more than just learn English and native manners. Rather, he argued, they “must be brought into complete harmony with our ideals and aspirations.” This was a widely held belief. In his book The Unmaking of Americans, the journalist John J. Miller has described how at the turn of the twentieth century, organizations such as the North American Civic League for Immigrants put out pamphlets celebrating the United States and helping immigrants understand and embrace the history and culture of their adopted country.

In the United States today, as in many Western countries, this kind of robust emphasis on assimilation has been replaced with multiculturalism, which holds that there is no single American culture, that immigrants and their descendants should retain their identity, and that the country should accommodate the new arrivals’ culture rather than the other way around. Bilingual education, legislative districts drawn along ethnic lines, and foreign language ballots are all efforts to change U.S. society to accommodate immigrants in a way that is very different from the past. Newcomers additionally benefit from affirmative action and diversity initiatives originally designed to help African Americans. Such race- and ethnicity-conscious measures encourage immigrants to see themselves as separate from society and in need of special treatment due to the hostility of ordinary Americans. John Fonte, a scholar at the Hudson Institute, has argued that such policies, which encourage immigrants to retain their language and culture, make patriotic assimilation less likely.Of course, many Americans still embrace the goal of assimilation. A recent Associated Press survey found that a majority of Americans think that their country should have an essential culture that immigrants adopt. But the kind of assimilation promoted by Brandeis and the North American Civic League no longer has elite backing. As a result, even institutions seemingly designed to help immigrants integrate end up giving them mixed messages. As political psychologist Stanley Renshon points out, many immigrant-based organizations today do help immigrants learn English, but they also work hard to reinforce ties to the old country.SHOW ME THE MONEYA further area of contention in the immigration debate is its economic and fiscal impact. Many immigrant families prosper in the United States, but a large fraction do not, adding significantly to social problems. Nearly one-third of all U.S. children living in poverty today have an immigrant father, and immigrants and their children account for almost one in three U.S. residents without health insurance. Despite some restrictions on new immigrants’ ability to use means-tested assistance programs, some 51 percent of immigrant-headed households use the welfare system, compared to 30 percent of native households. Of immigrant households with children, two-thirds access food assistance programs. Cutting immigrants off from these programs would be unwise and politically impossible, but it is fair to question a system that welcomes immigrants who are so poor that they cannot feed their own children. To be clear, most immigrants come to the United States to work. But because the U.S. legal immigration system prioritizes family relationships over job skills—and because the government has generally tolerated illegal immigration—a large share of immigrants are unskilled. In fact, half of the adult immigrants in the United States have no education beyond high school. Such workers generally earn low wages, which means that they rely on the welfare state even though they are working. This past fall, an exhaustive study by the National Academies of Sciences, Engineering, and Medicine found that immigrants and their dependents use significantly more in public services than they pay in taxes, and the net drain could be as high as $296 billion per year. The academies also projected the fiscal impact into the future with mixed results—four of their scenarios showed a net fiscal drain after 75 years, and four showed a net fiscal benefit. What is clear, however, is that at present the fiscal effect is large and negative. The study also showed, unsurprisingly, that college-educated immigrants are a net fiscal benefit, while those without a degree are typically a net fiscal drain. Drawing on the academies’ finding, the Trump administration has suggested moving to a “merit-based” immigration system that would select immigrants who can support themselves. Immigration has also affected the U.S. labor market. One of the nation’s leading immigration economists, Harvard’s George Borjas, recently wrote in The New York Times that by increasing the supply of workers, immigration reduces wages for some Americans. For example, only 7 percent of lawyers in the United States are immigrants, but 49 percent of maids are immigrants, as are one-third of construction laborers and grounds workers. The losers from immigration are less-educated Americans, many of them black and Hispanic, who work in these high-immigrant occupations. The country needs to give more consideration to the impact of immigration on the poorest and least-educated Americans. Another common argument for immigration is that it will solve Western countries’ main demographic problem—that of an aging population. Immigrants, so the argument goes, will provide the next generation of workers to pay into welfare-state programs. But to help government finances, immigrants would have to be a net fiscal benefit, which is not the case. Furthermore, the economist Carl Schmertmann showed more than two decades ago that “constant inflows of immigrants, even at relatively young ages, do not necessarily rejuvenate low-fertility populations… [and] may even contribute to population aging.” Analysis by myself and several colleagues supports this conclusion. In short, immigrants grow old like everyone else, and in the United States they tend not to have very large families. In 2015 the median age of an immigrant was 40 years, compared to 36 for the native-born. And the United States’ overall fertility rate, including immigrants, is 1.82 children per woman, which only falls to 1.75 once immigrants are excluded. In other words, immigrants increase the fertility rate by just four percent. The United States will have to look elsewhere to deal with its aging population. A final argument in favor of immigration centers on the benefits to immigrants themselves, especially the poorest ones, who see their wages rise dramatically upon moving to the First World. But given the scope of Third World poverty, mass immigration is not the best form of humanitarian relief. More than three billion people in the world live in poverty—earning less than $2.50 a day. Even if legal immigration was tripled to three million people a year, the United States would still only admit about one percent of the world’s poor each decade. In contrast, development assistance could help many more people in low-income countries.Even if legal immigration was tripled to three million people a year, the United States would still only admit about one percent of the world’s poor each decade.THE ART OF THE DEAL?

The last time that limiting immigration was on the U.S. legislative agenda, in the mid-1990s, Barbara Jordan’s commission suggested limiting family immigration and eliminating the visa lottery, which gives out visas based on chance. Clinton first seemed to endorse the recommendations, but then reversed course after Jordan died and the political winds shifted. The effort to lower the level of immigration was defeated in Congress by the same odd but formidable coalition of businesses, ethnic pressure groups, progressives, and libertarians that has dominated the immigration discourse from then until the Trump era.With the election of Trump, a political compromise in the United States might be possible. It could involve legalizing some illegal immigrants in return for tightening policies on who gets to come in. Prioritizing skilled immigration while cutting overall numbers would increase the share of immigrants who are well educated and facilitate assimilation. The RAISE Act, sponsored by Senators Tom Cotton (R-Ark.) and David Perdue (R-Ga.), would do just that. Perhaps coupling the RAISE Act with legalization for some share of illegal immigrants could be a way forward. Yet no matter what policy is adopted, immigration will remain contentious because it involves tradeoffs and competing moral claims. And for the foreseeable future, the number of people who wish to come to the developed countries such as the United States will be much greater than these countries are willing or able to allow.